Your Answer would be 1.74
The solution that will have the lowest freezing point is 5.0 SODIUM CHLORIDE.
Adding solute to solvents usually result in the depression of the freezing point. The higher the quantity of the solute that is added, the lower the freezing point of the solution.
The question is incomplete, here is the complete question:
Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and chlorine.
at 1,000 K
Calculate Kc for the reaction 
<u>Answer:</u> The value of
for the final reaction is 
<u>Explanation:</u>
The given chemical equations follows:

We need to calculate the equilibrium constant for the equation, which is:

As, the final reaction is the twice of the initial equation. So, the equilibrium constant for the final reaction will be the square of the initial equilibrium constant.
The value of equilibrium constant for net reaction is:

We are given:

Putting values in above equation, we get:

Hence, the value of
for the final reaction is 
Yes, it is possible to go do because it would be 2 stacks of 6